I believe they were only installed originally by snap fit on the backing plate. Based on my experience with both Murray and Briggs 4 drs.I would say that if you are fortunate enough to have a car with the original drip rails, it is only because someone in the past placed a screw to hold a rail in place that was probably getting loose enough to be a problem. Seems like many owners in the past got tired of them coming loose and yanked them off the car and threw them in the weeds.